Light emitting diodes (LEDs) are semiconductor-based light sources traditionally employed in low-power instrumentation and appliance applications for indication purposes and are available in a variety of colors (e.g., red, green, yellow, blue, white), based on the types of materials used in their fabrication. This color variety of LEDs has been recently exploited to create novel LED-based light sources having sufficient light output for new space-illumination and direct view applications. For example, as discussed in U.S. Pat. No. 6,016,038, incorporated herein by reference, multiple differently colored LEDs may be combined in a lighting fixture having one or more internal microprocessors, wherein the intensity of the LEDs of each different color is independently controlled and varied to produce a number of different hues. In one example of such an apparatus, red, green, and blue LEDs are used in combination to produce literally hundreds of different hues from a single lighting fixture. Additionally, the relative intensities of the red, green, and blue LEDs may be computer controlled, thereby providing a programmable multi-channel light source, capable of generating any color and any sequence of colors at varying intensities and saturations, enabling a wide range of eye-catching lighting effects. Such LED-based light sources have been recently employed in a variety of fixture types and a variety of lighting applications in which variable color lighting effects are desired.
These lighting systems and the effects they produce can be controlled and coordinated through a network, wherein a data stream containing packets of information is communicated to the lighting devices. Each of the lighting devices may register all of the packets of information passed through the system, but only respond to packets that are addressed to the particular device. Once a properly addressed packet of information arrives, the lighting device may read and execute the commands. This arrangement demands that each of the lighting devices have an address and these addresses need to be unique with respect to the other lighting devices on the network. The addresses are normally set by setting switches on each of the lighting devices during installation. Settings switches tends to be time consuming and error prone.
Lighting systems for entertainment, retail, and architectural venues, such as theaters, casinos, theme parks, stores, and shopping malls, require an assortment of elaborate lighting fixtures and control systems therefore to operate the lights. Conventional networked lighting devices have their addresses set through a series of physical switches such as dials, dipswitches or buttons. These devices have to be individually set to particular addresses and this process can be cumbersome. In fact, one of the lighting designers' most onerous tasks—system configuration—comes after all the lights are installed. This task typically requires at least two people and involves going to each lighting instrument or fixture and determining and setting the network address for it through the use of switches or dials and then determining the setup and corresponding element on a lighting board or computer. Not surprisingly, the configuration of lighting network can take many hours, depending on the location and complexity. For example, a new amusement park ride may use hundreds of network-controlled lighting fixtures, which are neither line-of-sight to each other or to any single point. Each one must be identified and linked to its setting on the lighting control board. Mix-ups and confusion are common during this process. With sufficient planning and coordination this address selection and setting can be done a priori but still requires substantial time and effort.
Addressing these disadvantages, U.S. Pat. No. 6,777,891 (the “'891 patent”), incorporated herein by reference, contemplates arranging a plurality of LED-based lighting units as a computer-controllable “light string,” wherein each lighting unit constitutes an individually controllable “node” of the light string. Applications suitable for such light strings include decorative and entertainment-oriented lighting applications (e.g., Christmas tree lights, display lights, theme park lighting, video and other game arcade lighting, etc.). Via computer control, one or more such light strings provide a variety of complex temporal and color-changing lighting effects. In many implementations, lighting data is communicated to one or more nodes of a given light string in a serial manner, according to a variety of different data transmission and processing schemes, while power is provided in parallel to respective lighting units of the string (e.g., from a rectified high voltage source, in some instances with a substantial ripple voltage). In other implementations, individual lighting units of a light string are coupled together via a variety of different conduit configurations to provide for easy coupling and arrangement of multiple lighting units constituting the light string. Also, small LED-based lighting units capable of being arranged in a light string configuration are often manufactured as integrated circuits including data processing circuitry and control circuitry for LED light sources, and a given node of the light string may include one or more integrated circuits packaged with LEDs for convenient coupling to a conduit to connect multiple nodes.
Thus, the approach disclosed in the '891 patent provides a flexible low-voltage multi-color control solution for LED-based light strings that minimizes the number of components at the LED nodes. In view of the commercial success of this approach, the lighting industry desires longer strings with more nodes for complex applications.